Color printing error

I am trying to print something in full color sandstone with some textures mapped to it.
I am using Blender to do the UV mapping.
I can get the .wrl into mesh lab such that it shows the textures, but when I upload the same file to Shapeways (zipped of course with the images) the texture is not there. I will say that I have 2 separate closed objects that overlap. Could this be why the textures are not showing up in my 2D view?

I have gotten the texture to show up when I upload a file with just one object.

Shapeways only supports UV textures, no other texture projections.
You can only use bitmap textures (no 'procedural' shaders').
Texture files must be in JPG or PNG format.You can use more than one texture map on your object, but the maps are not allowed to overlap â€“ the printer cannot figure out which texture to print in that case.The last limitation is the resolution of your texture â€“ we recommend you keep the total resolution of your texture maps below 2048x2048 pixels. For example, if you need 4 textures, keep them all below 1024x1024 pixels.

I have spent a few hours this evening troubleshooting my problem. My model has 43 mesh objects. I have taken a stepped approach by creating VRML files which first exported just some of the objects with the materials applied. Things were working fine as I continued to add objects and upload them to shapeways. The colors were displaying correctly and I was wondering why when I uploaded my initial model it didn't work. Well as I continued adding all the objects shapeways began to confuse the materials and objects began having the wrong colors on them.

See the attached image.
In the first frame of the image things are fine. You can see I have my texture showing up on my model and also an orange material on the gloves, grey material on the arms and a red material on the glove bands.

In the next frame of the image things are still fine. I have just added shoes and legs and applied the materials.

In the next frame of the image things start going wrong. I added an eye and some spikes to the shoes. The spikes don't have a material applied. The eye had a blue material applied in blender but it shoes up as the orange material. Also now the legs and the shoe soles have become orange also.

In the next frame of the image I just added spikes (with no material applied) to the glove bands and now just about everything but the glove bands and arms are orange.

[Edit: added another frame to the image.]
In the next frame all I did from the previous frame was move the eye and the glove and foot spikes away from the rest of the model...and you can see the body now has the correct color again. But most of the items are still the wrong color. But the point is that the proximity of the objects seems to influence the color interpretation.

Can anyone explain why this is happening? Should I be doing something different in Blender to avoid this problem?

Maybe the new unification process destroys UV coords and/or image references? Other people have complained about missing parts or totally deformed zones, so maybe it has bugs. It would be nice to keep for the volume calculations, but booleans with meshes are like playing with matches in the munitions dump. Before things were printed fine without, so the printers probably don't care about united meshes.

Try to union your meshes in your own software and you will possibly see the same behaviour. I would suspect issues with one of your meshes or texture maps which only surface with the boolean operation.

In our experience, Shapeways' unification/repair process will produce the same results as the union operator in other software.

If nothing else, your unified mesh will no longer need to be post-processed by Shapeways' repair ...

Are you talking about a boolean union? I have always read to avoid boolean operations whenever possible.
Additionally when I use it in Blender with my model I begin to get non-manifold errors. The boolean union doesn't result in a watertight mesh.

It sounds like that... basically, you are between sword and wall. Well, now everyone is with color material, as it reduces how you can model things or increases the computer resources and time to get it done.

New design rules better cover this, because new system makes design for color different from other materials where you just keep it watertight and it works. If anybody knows a software that does mesh booleans perfectly 99.99% of times, please say so, as most software has issues sooner and later.

As far as I can tell, that meshmedic thing is basically an enhanced Netfabb repair followed by a boolean union. If you cannot clean your meshes to the point that the union works in your software, chances are high that the meshmedic process fails as well.

I've only done boolean unions in Blender, which typically produces messy results that need a lot of cleanup, and often fails to do anything (with my admittedly limited computing resources). This is with meshes that are manifold to begin with. Uploading color files would definitely be a lot easier (for newbies, at least) if we didn't have to worry about the results of a boolean union.

Since the union is apparently only needed in order to get a correct volume calculation, couldn't Shapeways do it just for this purpose (ignoring the UV maps), and keep the original mesh (or repaired mesh, if the original isn't manifold) for printing?

I analysed your model and I believe that you're the first to run into a limitation of our renderer: we're currently limited to displaying 16 different materials on an object. During VRML importing, our (Blender) script collects the separate parts and joins them together.

I believe that during the collection of separate parts, it will create new materials for each one - even if they are the same as previously defined materials. The later version of your model (with the spikes) has 43 separate objects.

Could you mail me the original .blend file so I can run a few tests on that and verify my theory? I'll try to pre-join similar parts in Blender before exporting them (like joining the arm parts together, and join the shoe parts together). I'll make sure I don't have more than 16 parts, and check if the upload succeeds in this case.

This is a bit if a kludge, I know. The renderer is on our todo list, so I'll add a note about this problem.

The workaround i've suggested above works well - it took me too many hours to dig out this solution.

I just uploaded test #3 another full color test model with accurate intact textures.

The best solution so far that i came up during all the "research" that i've been doing lately with full color printing, exporting/importing back and forth using many 3d software tools and which unfortunately shapeways software doesn't recognize - is a very cool utility which was written by am Italian student that basically "bakes" the textures into the model.

The end result is a single wrl file with NO textures.
Meaning.. no textures/parts mess which is perfect for every one not just newbies.

Again unfortunately only Cortona3D viewer for Firefox can display this file... other tools including meshlab 1.3.0b don't.

But beside all that... shapeways has ignored too many requests on the forum by practically anyone about that wax coating that kills the white color and subsequently dims all other colors.

I sent another color model to print with a request to CS not to coat it with wax - hopefully it will arrive with vivid colors.
I will coat it myself with a simple clear epoxy quick-dry spray.
This worked great before.